1. Technical Field
The embodiments disclosed herein are related to the field of light emitting diode (LED) devices.
2. Background and Relevant Art
Unless otherwise indicated herein, the materials described in this section are not prior art to the claims in this application and are not admitted to be prior art by inclusion in this section. The use of the term “background” is inclusive of the term “context.” Thus, the following section provides both context for the disclosure and may also provide patentable support for the claims.
The use of doped semiconductors to create barriers, injectors, tunnel junction contacts, cascade LED junction, and other related device has long been known in the art. Specially, conventional semiconductor materials can be comprised of doped semiconductor layers placed into contact with each other to create one or more p-n junctions. In the case of light emitting diodes (LEDs), as electrical current is applied to the junctions, electrons and holes combine with each other and emit photons. The energy contained in the emitted photos corresponds to the energy difference between the respective holes and electrons.
Conventional LED device dies have dimensions around one millimeter square and a tenth of a millimeter thick. The die substrates have thin semiconductor heterostructure layers on one side, with the layers patterned by lithography for making electrical contact. Forcing an electrical current through the heterostructure layers can convert electrical power to optical power. Light generated within the heterostructures can be extracted from a die with combinations of surface features and coatings, such that light can escape which would otherwise be mostly confined to the die because of total internal reflection.
High-brightness light emitting diode (LED) chips are also known. These chips can emit light with wavelengths that fall in the near-infrared, visible, or ultraviolet spectral ranges. High-brightness LEDs require several unique design considerations. For example, design considerations for High-brightness LEDs may also involve packaging, thermal management, electrical control, and optical guiding considerations.
In some conventional systems, the dies are mechanically attached, using eutectic bonds or conducting epoxy, to thermally conductive LED packages, which have been specifically developed to dissipate the waste heat from high-brightness LED die. The dies are typically electrically contacted with wire bonds to their surfaces. The electrical drive and control of current through high-brightness LEDs is typically accomplished using specialized integrated circuits developed for the power, voltage, and thermal regulation requirements of high-brightness LEDs.
Semiconductor hetero structures based upon antimonide-arsenide semiconductor materials have been researched and developed for their uses as mid-infrared light emission structures. The great design flexibility available from combinations of these materials has more generally led to interest and developments for transistors, optical detectors, and light emitters.
For mid-infrared light emission, the emission wavelength from a device can be set using bulk alloys, superlattices, or quantum wells. Antimonide-arsenide superlattices and quantum wells are of particular benefit because they can also be engineered to mitigate material loss mechanisms that are prominent difficulties at mid-infrared wavelengths, such as the loss mechanisms of free-carrier absorption and Auger recombination.
Another useful property available with some antimonide-arsenide layer combinations is the ability to form interband tunnel junctions, which allows for light emission stages to be cascaded. Several combinations of antimonide-arsenide layers can provide a double-heterostructure confinement configuration for confining charge carriers to the light emitting alloys, superlattices, or quantum wells.
LED device structures based upon antimonide-arsenide heterostructures have been researched and developed at a few mid-infrared emission wavelengths using various particular devices configurations for the particular wavelength. However, from about 3 to 20 μm, there are wavelength ranges for which LEDs have not been reported. Additionally, high-brightness mid-infrared LEDs based upon antimonide-arsenide heterostructures have not been reported.
Together, the technologies for mechanical packaging, thermal management, electrical control, and optical guiding provide a broad technology base for high-brightness LEDs. This technology base accommodates the semiconductor materials and properties employed for LEDs operating at near-infrared, visible, and ultraviolet wavelengths. However, there are not corresponding mid-infrared high-brightness LEDs, which might take advantage of this technology base, and there are not corresponding mid-infrared high-brightness LEDs with their own supporting specialized industrial technology base. Accordingly, there are a number of improvements that can be made within the art.